1. Field of the Invention
The present invention relates to an amplifying apparatus.
2. Description of the Related Art
An amplifier used for amplifying high-frequency signals used in wireless communications generally has superior power added efficiency (PAE) in the vicinity of a maximum output. However, in a communications apparatus such as a mobile phone or the like in which the amplifier is used, use frequency at a maximum output level may be low, while use frequency at a relatively low output of about 10 dB to about 20 dB may be high.
For this reason, in the above-described communications apparatus, PAE having the low output of about 10 dB to about 20 dB greatly affects a continuous use time of a communications apparatus driven by internal power from a battery, or the like.
In this regard, technologies for switching an amplifier used in the amplification of high-frequency signals in accordance with output power required for an operation have been developed. As an example of technologies for switching a maximum output power for each of a plurality of operation modes, the following Related Art Document, may be provided as an example.
As a power amplifier, a high-performance bipolar transistor such as an InGaP heterojunction bipolar transistor (hereinafter, referred to as “HBT”) or the like has been used.
Meanwhile, as a switch for switching the amplifier, a high electron mobility transistor (HEMT), a GaAs-based compound semiconductor has generally been used.
For this reason, such as an amplifying apparatus using technology disclosed in the following Related Art Document, an amplifying apparatus (or an amplifier module) that can switch the amplifier used in the amplification of high-frequency signals in accordance with the output power required for device operation is required to combine, for example, a plurality of semiconductor chips to thereby include the combined semiconductor chips, thereby causing an increase in manufacturing costs or unit size.
In addition, in recent years, a complex process that may configure the InGaP HBT and the HEMT as a single semiconductor chip has been developed.
However, since the above-described process is complex, an increase in costs may be caused when it is applied.